Fire-control apparatus, determination of quadrant of enemy&#39;s course



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A. BARR ET AL.

FIRE CONTROL APPARATUS, DETERMINATION OF QUADRANT 0F ENEMY'S COURSE Filed Sept. 6, 1923 a Shawn's-shes: 1

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Draftsman Dec. 9, 1924- A. BARR ET AL FIRE CONTROL APPARATUS, DETERMINATION OF QUAURANT OF ENEMYS COURSE Filed Sept. 6, i923 3 Sheets-Sheet 3 a I 9w L in v @EEEEEEEE 2 i Mm (@Wwwmz-Msm,

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Patented Dec. 9, 1924.

UNITED STATES PATENT OFFICE.

ARCHIBALD BAR-R AND WILLIAM STROUD, OF GLASGOW, SCOTLAND, ASSIGNORS TO BARR AND STROUD, LIMITED, OF GLASGOW, SCOTLAND.

FIRE-CONTROL APPARATUS, DETERMINATION OF QUADRANT OF ENEMYS COURSE.

Application filed September 6, 1923.

To all whom it may concern:

Be it known that we, ARCHIBALD BARR and IVILLIAM STRoUD, subjects of the King of Great Britain and Ireland, and both of Caxton Street, Anniesland, Glas ow, Scotland, have invented new and useful lmprovements in Fire-Control Apparatus, Determination of Quadrant of Enemys Course, of which the following is a specification.

The object of our invention is to determine, when an enemy ship is at or near the broadside-on position whether the fore-and-aft line lies in the quadrants X Z or Y IV (Figure 17 of the drawings to be referred to), where V T represents the line of sight, by which means (knowing which way the enemy is steaming) we can determine whether the component of the enemys ve locity along the line of sight is towards or from our own ship or fort. We shall confine our attention in the first instance to the case of observations from a single ship.

In describing this invention reference will first be made to Figures 1, 2, 3, 4, 5, 6, 7, 8 and 17 of the drawings which are diagrams.

)Ve install two instruments (hereinafter referred to as goniometers) capable of accurately measuring small angles in a horizontal plane, the one in a fore and the other in an aft position at as great a distance apart B as is practicable. The. observers at the two goniometers are in telephonic (or other) communication with each other and they arrange to work upon two definite points of the target, say, e. g., the bow and the stern, and to measure the horizontal angle subtended by these two points at the two goniometer stations A and C.

In Figure 1, A and C are the two stations and T represents the target, the angle of hearing as at G being represented by T C A. Now it is clear that the goniometer angle as measured from O requires correction before it is compared with the goniometer angle as measured from A because the distance C T is greater than A T. Drop a perpendicular from A on C T, viz, A P; then T A is sensibly equal to T P, remembering that T is usually at a very great distance R away; i. e. R is very great compared to B. If the Serial No. 661,309.

goniometer angle as measured from C is multiplied by the ratio TC we get the value of the angle as though measured from P and this angle is strictly comparable with the angle as measured from A.

In Figure 2 we suppose that we are dealing with this multiplied angle at P and the actual goniometer angle at A. Let T T be the tWo points of the target with which we are dealing; then the measured goniometer angle at A is the angle T A T while the multiplied angle at P is T P T Let a perpendicular from the middle point of T T be drawn and suppose the line T T be oriented so that this perpendicular bisects P A at the point Q. Then it is clear that the angles T A T and T P T will be equal. The target is now exactly broadside on to the point Q. Suppose T T to turn through a very small angle in the direction .of the arrow; then the perpendicu lar to T T will gradually approach A and recede from P while the angle subtended by T T at A will get larger and that at P will get smaller. Thus the criterion that the target is exactly broadside on (at all events to the point Q) is that the two angles shall be exactly equal.

If the target is in motion in the direction T T then, if the goniometer angle at A is greater than the angle at P, the target is moving away and vice versa.

If or represents the angle P C A, and R the range, we require mechanism for multiplying the goniometer angle measured at Gby TO T i. e. by

R+B (305 a R or by 1+%cos a and mechanism for comparing this angle with the goniometer angle at A,

One way of simply accomplishing the objcct in view is by means of a Wheatstone bridge circuit. Figure 3 shows such a circuit with supply wires resistances 0 and a proportional to the goniometer angles measured at G and A respectively, the other resisgances being as shown proportional to 1 an 1+g cos a,

while G is the galvanometer. WVhen the galvanometer is balanced we have 1 cf B 1+ cos a 1+? cos a)=a the angle at Pzangle at A v or target in broadside-on position.

Thus a deflection of the galvanometer pointer to one side of the zero, see Figure 17, will indicate one pair oi quadrants Y and l/V, while a deflection to the other side will indicate the other pair X and Z.

As the goniometer angle at A is being measured, we have mechanism for varying proportionally the value of the resistance a, in the well known manner. The same remark applies to C and 0, except that 0 may be conveniently situated in the region of C, in which case we may have low resistance cables to and from the station A or the resistance of these cables may be allowed for in the construction of the resistance 0.

The adjustment of the arm of the bridge to the value 1+ cos a COS (I This could be done (since there are two variables only) by a multiple cam such as is described in specification of United States Patent No. 1,460,221 or some simple mechanical device can be employed.

The accuracy will of course depend on the magnitude of B, T T and the smallness of R. In the case where the stations A and C are 011 land, the value of B can usually be made great. In order to increase the accuracy at sea by using a larger value of B we may use two goniometers as before but one on one ship and the second one on a sec- 0nd ship. The electrical equipment will now be upon one of these ships and we must possess means of measuring the value of B (the distance between the two goniometers) and the value of the angle T G A at the distant goniometer C. B may be measured in any well known manner. The Wheatstone bridge circuit can now conveniently be arranged after the manner of Figure 4 where the arms are now a, a, R and R+B cos oz. Having measured the value of B that value will be utilized for the determination of the value of B cos oz by known methods, while the slider S is set to the known value of B.

Any convenient signalling method may be used for transmitting the reading of the distant goniometer. We may e. g. have the equivalent of a large clock-face associated with the mechanism which measures the distant angle and observe the time with a telescope at the near station and set off this time 011 a corresponding miniature clockface associated with the mechanism for adjusting the value of c. The minute hand of the large clock may be replaced by a point er moving through one revolution for ten seconds of angle, and the hour hand (if necessary) by a smaller pointer moving through one revolution for one hundred seconds of angle. We shall start at the near station by adjusting the value of 0 so that the galvanometer is roughly balanced and then adjust the seconds accurately by means of the clocks.

A second method of carrying out our purpose is by means which may be shortly described as a mechanical equivalent of a lVheatstone bridge system :Suppose, see Figure 5, we set oil R mechanically along the line 0 D and along the line D F simultaneously (say) and by means of a differential gear (or its equivalent) we add on a part F E B cos 0:; then if we have an arm O H pivoted at O and passing through E the angle E 0 D 6 is a measure of theratio R+B cos ouR. Similarly, see Figure 6, if we set oil 0 D proportional to c and D E proportional to n, the angle E O D 0 is a measure of the ratio azc. Thus the Vheatstone bridge condition is satisfied if 0:6 It will be noticed that as B cos a is very small compared with R the angle (9 is always in the neighbourhood of 45. at all events if the horizontal and vertical scales are to the same scale.

There are a very large number of ways of observing the equality of the angles 6 and 0 of which only a few will be mentioned; 0. g. 1) we may place Figure 6 over Figure 5 with 0 above 0 and the line 0 1) above 0 D; then, if the line 0 H falls 011 O H, we have equality; (2) the angle 0 may be mechanically communicated to one element of REGlQTEHiLh a differential gear, the angle 0 to the third element in the opposite sense when a pointer attached to the jockey element will indicate the difference (if any) between 6 and 6 (3) we may arrange the parts as in (1),

1+? cos a=%' Now in Figure 7 let 0 F beset off to represent R, let F E be set off to represent B cos a, and in Figure 8 let 0 P represent 0 and P E represent a- 0 (obtained by differential gear from (a and 0) then we may test the equality of the angles E O F and E O P as already described.

Some examples of construction according to this invention will now be described with reference to Figures 9, 10, 11, 12, 18, 14, 15 and 16 of the drawings, in which Figure 9 shows a known form of sliding resistance.

Figure 10 shows a method of effecting the adjustment according to the lower part of Figure 4.

Figure 11 is a plan and Figure 12 is a sectional view, the section taken being about the line 21 of Figure 11, showing an arrangement of construction corresponding to Figure 7.

Figure 13 is a plan and Figure 14 is a sec-- tional view, the section taken being about the line 21 of Figure 13, showing an arrangement of construction corresponding to Figure 8.

Figure 15 is a plan view and Figure 16 is a side view of the two instruments combined to test the equality or otherwise of the angles 0 and 0 shown in Figures 7 and 8.

In Figure 9 we have a uniform resistance wire wound as a spiral on an insulating drum. A brush 1 fixed to nut 2 on screw 3 is actuated by handle 4 which may (in certain cases) actuate the measuring apparatus of one of the goniometers; thus the resistance between and the brush 1 may become a measure of one of the goniometer angles. Suitable gearing is provided between han dle 4 and the axis of the drum on which the wire is wound, so that, as 4 is rotated moving brush 1 along screw 3, the drum is also rotated at a suitable rate so that the brush moves continuously along the wire.

In Figure 10 the two arms R and R B cos a of the WVheatstone bridge circuit Fig ure 4 are shown together with the slider S. The value of R is communicated to handle 5, to which is fixed wheel 6 gearing with wheels 7 and 8 fixed to drums 9 and 10 respectively. Screw 11 carrying slider S as a nut is also fixed to 5, whose rotation in accordance with B may be produced by an electrical receiver geared thereto or, if 5 is directly operated by hand, suitable means (not shown) for indicating the value of B may be associated with 5. The electrical resistance corresponding to- R on the left is represented by the resistance of the wire between brush 12 and slider S. On the right hand side we have to make allowance for the term B cos a which may be or The value of oz is communicated (automatically or otherwise) to screw 16 by means of handle 15 fixed to it. Nut 17 has a brush moving over a series of studs 18 (the middle one at 19 corresponding to the value a 90); between successive studs are inserted I resistance wires corresponding to the values of (Z (cos a), i. e. of sin a. The figure is drawn for the case when a 90 in which case B is the resistance between the middle stud at 19 and slider S.

lVhcn a is in the position of Figure 1, nut- 17 will be upon the upper series of studs (Figure 10) while when on is greater than 90, it will be upon the lower series. Thus if the values of R and oz are continuously communicated tothe apparatus illustrated in Figure 10 and the values of 0 and a communicated to the other arms of the Wheat stone bridge, as shown diagrammatically in Figure 4 but not shown in Figure 10, the defiection of the galvanometer to one or the other side will give the pair of quadrants in which the fore-and-aft line of the target ies.

Figures 11 and 12 show an arrangement of construction corresponding to Figure 7. Here 22 is the range receiver geared to screw 23 on which is threaded nut 24 (suitably guided) supporting a fiat rod 25 comprising a rack 26 at its distant end. This rack gears with a long pinion rod 30. Carried on the rod 25 is a swivelling pin 27 provided at the upper end with a forked piece 28 in which a flat bar 29 can slide. 29 is pivoted to rock about a fixed pin 81.

The value of a is communicated to shaft 40 carrying arm 41 to which is fixed pin 42, the distance between the centres of 40 and 42 representing on the selected scale the base b of Figure 1. In the case of two ships being engaged in the operations, provision must be made for adjusting the radial distance of 42 from 40. Pin 42 engages in a slot 43 of a suitably guided frame 44 carrying a rack 45 engaging with a pinion 16 fixed to 30. As oz varies in value, the frame 44: will be moved in its slide, thus rotating pinion rod 30 and translating rack 26 and thereby translating pin 27 and rocking bar 29 about pin 31. A mark 48 at the upper end of 29 indicates by its position the value of the angle at O, Figure 7.

Figures 13 and 14 show an arrangement of construction corresponding to Figure 8. 22 represents an electrical receiver giving the value of 0. The part 25 of Figures 13 and 14: corresponds to and functions as the part 25 of Figures 11 and 12, so 22 corresponds to 22 etc. etc., up to 31 to 31, and need not be again described.

The value of a is communicated to bevel wheel 71 either by direct gearing, if the apparatus is situated at A, Figure 1, or, if at a distant station, by receiver 70. By means of pinion 73, fixed to screw 23 the value of 0 is communicated to toothed and bevel wheel 72. 74 is the jockey wheel of the differential gear 71, 7 1, 72. The spindle of 74 is fixed to long pinion rod 30 the rotation of which gives a measure of (4-0, which is communicated to rack 26 and pin 27 thus angling 29 carrying a mark 48 about its fulcrum 31 Figures 15 and 16 show the two instruments illustrated in Figures 11 and 12 and Figures 13 and 14: after superposition, that of Figure 11 being placed above that of Figure 13. In Figure 15 it will be seen that pointer 48 is in coincidence with pointer 48 corresponding to the broadside-on position. If 48 had been to the right or left of 48 one or other of the quadrants X Z or Y 1V, Figure 17, would have been indicated.

1. Apparatus comprising two goniometers (instruments capable of measuring small angles in a horizontal plane), situated at a distance apart, means associated with one of the goniometer-s for multiplying the angle determined by that goniometer by the ratio (Figure 1), for the purposes set forth.

2. Apparatus comprising two gonio-meters situated at a distance apart and means for correlating the two measured angles whereby when (1) the range of the target, (2) the distance between the two goniometers and the angle a, the angle between the line of sight and the base, are known, the sign of the deviation from the broadside on position may be indicated.

3. Apparatus comprising means for determining from each of two positions at a distance apart the horizontal angle subtended at each of these positions by two definite points on a target and a lVheatstone bridge circuit for multiplying one of the angles determined by the ratio (Figure 1), for the purposes set forth.

4. Apparatus comprising means for determining from each of two positions at a distance apart the horizontal angle subtended at each of these positions by two definite points on a target and a mechanical equivalent of a WVheatstone bridge circuit for multiplying one of the angles determined by the ratio (Figure 1), for the purposes set forth.

5. Apparatus comprising means for determining from each of two positions at a distance apart the horizontal angle subtended at each of these positions by two definite points on a tar et, a lVheatstone bridge circuit, means for varying the resistance of one of the arms 0 proportional to the goniometer angle at C (Figure 1), means for varying the resistance in another arm a proportional to the second goniometer angle as measured at A (Figure 1) and means for varying the resistances of the two remaining arms of the bridge to be made proportional (1) to the range R and (2) to the sum of R and B cos a, the resistances a and R being arranged opposite to one another in the circuit.

6. Apparatus comprising two goniometers for determining from each of two positions at a distance apart the horizontal angle subtended at each of these positions by two definite points on a target, a Vheatstone bridge circuit, means for varying the resistance of one of the arms 0 proportional to the goniometer angle at C (Figure 1) means for varying the resistance in another arm a proportional to the second goniometer angle as measured at A (Figure 1) the resistances of the two remaining arms of the bridge being proportional to 1 and tended at each of these positions by two defi- 1 nite points on a target, geometrical means for n1ult1plymg one of the goniometer angles determined by the ratio Figure 1, consisting of a first part set out with means for exhibiting the value of 19,

that is R-l-B cos a a means for exhibiting the ratio of Z and tanmeans for indicating differences between 6 and 0 0 being Bcosa means (Figure 8) for setting out the value of 0 and for. setting out laterally thereto, preferably perpendicularly thereto, the value tan* of the difierence (4-0 between the two goniometer angles, and means (Figure 8) for exh1b1t1ng the Value of tan 9. Apparatus for use in determining the sign of the deviation (whether plus or minus) of the keel line of an enemy ship from the broadside-on position, comprising two goniometers and means for multiplying the goniometer angle observed at one of the stations (say, the station O) by the ratio LIE T]? (Figure 1) so as to give the value of the goniometer angle as measured from an imaginary station P situated at substantially the same distance from the target as the other station A.

10. Apparatus according to claim 9 comprising the use of :two goniometers at as great a distance apart as possible, associated with means for correlating the two measured angles whereby when (1) the range R, (2) the distance between the two goniom'eter sta tions B, and (3) the angle 0: between the line of sight and the base B are known the sign of the said deviation may be indicated.

ARCI-IIBALD BARR. WILLIAM STBOUD. 

